1. Field of the Invention
The present invention relates to a pressure transmitting passage of an evaporative fuel treating apparatus, and particularly to a pressure transmitting passage of an evaporative fuel treating apparatus which is provided in a fuel tank provided in a vehicle such as an automobile.
2. Description of the Related Art
There has conventionally been known a pressure transmitting passage of an evaporative fuel treating apparatus which is provided in a fuel tank provided in a vehicle such as an automobile. An example thereof is described in Japanese Patent Application Laid-Open (JP-A) No. 7-180627.
As shown in FIG. 8, applied to a vehicle is an onboard vapor recovery system (i.e., OVR system) in which, during fueling by using a fuel filling gun 70, evaporative fuel generated from a fuel tank 72 is sucked by a canister (not shown) connected to a vapor line 73. The fuel tank 72 is disposed below a floor panel 74. A fuel filling pipe 76, a vent pipe 78, and a pressure control line 80 serving as a pressure transmitting passage are each provided to extend from the fuel tank 72 to a fueling port 84 formed in a side wall portion 82 of the vehicle.
However, in the above-described structure, the pressure control line 80, whose one end portion is connected to a differential pressure regulating valve 88 disposed above the fuel tank 72, extends from the fuel tank 72 and below a side member 86 which is provided along a longitudinal direction of the vehicle at a lower surface side of the vicinity of a vehicle transverse direction outer end portion of the floor panel 74, such that the pressure control line 80 is connected to the oil feeding port 84 disposed at a position above the fuel tank 72. Hill portions 80A, 80B and a dale portion 80C are thus formed in the pressure control line 80.
Accordingly, in a state in which a liquid fuel 90 remains in the dale portion 80C of the pressure control line 80 due to fueling, traveling of the vehicle, condensation, or the like, because the amount of the liquid fuel being fed by the fuel filling gun 70 is greater than the amount of air flowing through the vent pipe 78, the internal pressure of the fuel tank 72 increases and the liquid fuel 90 remaining in the dale portion 80C of the pressure control line 80 is pushed up from the dale portion 80C to the portion 80B of the pressure control line 80 in the vicinity of the oil feeding port 84. When the pressure generated by the liquid fuel column of the liquid fuel 90 and the internal pressure of the fuel tank 72 become equal to each other, no difference in pressure between a low pressure chamber 88A and a high pressure chamber 88B of the differential pressure regulating valve 88 arises, and accordingly, the differential pressure regulating valve 88 does not open. For this reason, the internal pressure of the fuel tank 72 continues to rise, and subsequently, the filled liquid fuel flows backward within the fuel filling pipe 76, which causes a sensor of the fuel filling gun 70 to respond so as to stop the fueling operation before the fuel tank 72 is full.
Meanwhile, with regard to the present invention, there is disclosed a vent system of a fuel filling pipe in which a chamber is provided in a vent pipe of the fuel filling pipe so as to enlarge the vent passage (see Japanese Patent Application National Publication (Laid-Open) No. 7-502227).